Direct evidence for magnetohydrodynamic disk winds driving rotating outflows in protostar HOPS 358

Angular momentum removal is a fundamental requirement for star and planet formation, yet the mechanisms driving this process remain debated. Magnetohydrodynamic disk winds, launched along magnetic field lines from extended disk regions, offer a promising solution, particularly in regions where magnetorotational turbulence is weak. Here we present high-resolution Atacama Large Millimeter/submillimeter Array observations of the Class 0 protostar HOPS 358, revealing a rotating, nested outflow structure traced by H2CO, SO, and CH3OH emission. The outflow preserves the disk’s rotational sense and is aligned with the disk axis, providing direct observational evidence for a magnetically launched disk wind. From the measured kinematics, we derive a dimensionless magnetic lever arm of approximately 2.3 and constrain the wind-launching region to radii of 10-18 astronomical units within the planet-forming zone. These results demonstrate that magnetohydrodynamic disk winds operate during the deeply embedded phase, efficiently extracting angular momentum while shaping disk evolution and establishing initial conditions for planet formation. Understanding how young forming stars shed angular momentum is key to star formation. Here, the authors show that a rotating outflow from a deeply embedded protostar is driven by a magnetically launched disk wind that removes angular momentum by ejecting material across a broad range of disk radii.